Merge pull request kothariji#108 from gothira/master

Binary code problem.

Author: kothariji

Binary code problem (Hackerrank)

@@ -0,0 +1,69 @@
+/*Binary Code
+ 
+You are given a sequence of bits (a binary string) of length N. You need to generate a list of binary strings of length N starting from the given binary string. There can be no repetitions in the list, and any two consecutive binary strings in the list should differ by only one bit.
+
+For example, assume you are given the binary string 0010. binary strings 0010 and 0110 differ only by one bit; 0010 and 0111 differ by two bits; 0010 and 0010 are the same; 0200 is not a binary string; 100 is not a binary string of length 4, while 0100 is a binary string of length 4.
+
+This problem has partial scores. If your list is valid, then your score for that test case is {L\over 2^N}S, where L is the number of binary strings in your list and S is the allocated score for the test case.
+
+Input Format
+The input will contain a non empty string of 0’s and 1’s indicating the initial binary string.
+
+Constraints
+1 ≤ N ≤ 16  
+Limits
+Time Limit: 1s
+Memory Limit: 256MB
+Output Format
+First line of the output should contain a single integer L, the number of strings in your list. L lines should follow, the list of values.
+
+Sample Input
+0010
+
+Sample Output 0
+6
+0010
+1010
+1000
+1100
+0100
+0000
+*/
+
+//Solution.
+
+#include <iostream>
+#include <algorithm>
+#include <vector>
+#include <string>
+#include <sstream>
+#include <map>
+#include <set>
+#include <cmath>
+#include <cstring>
+#include <cstdio>
+
+using namespace std;
+
+string s;
+
+void change(int n) {
+    if (n >= s.size()) {
+        cout << s << endl;
+        return;
+    }
+
+    change(n + 1);
+    s[n] = s[n] == '0' ? '1' : '0';
+    change(n + 1);
+}
+
+int main() {
+    cin >> s;
+
+    cout << (1 << s.size()) << endl;
+
+    change(0);
+
+    return 0;
+}